@article {48701,
	title = {Multi-bandgap quantum dots ensemble for near-infrared photovoltaics},
	journal = {Energy Technology},
	volume = {11},
	year = {2023},
	month = {JUN},
	type = {Article},
	abstract = {<p>
	Narrow bandgap quantum dots (QDs) are an important class of materials for near-infrared (NIR) optoelectronic devices owing to their size-tunable bandgap and chemical root processing. In photovoltaic applications, NIR QDs could be particularly useful to complement the sub-bandgap transmission loss of NIR solar radiation from perovskite and c-Si solar cells. However, insufficient carrier extraction thickness associated with the narrow NIR excitonic bandwidth of QDs limits the conversion efficacy of the broad NIR solar spectrum. Here, we utilize a multi-bandgap QD ensemble which widens the NIR absorption bandwidth to mimic the broad solar spectrum. A solution-phase ligand passivation strategy is used to control doping properties and energy level alignment of multi-bandgap QDs. We successfully developed bulk-heterojunction solar cells using the multi-bandgap QD ensemble, which yields higher carrier extraction thickness and broader NIR absorption. The gain from NIR absorption and carrier transport resulted in higher short-circuit current generation and power conversion efficiency (PCE) in solar cell devices. The champion device shows 8.73\% PCE under 1.5 AM solar illumination and 7.44\% and 5.05\% PCE for the NIR photons transmitted from perovskite and c-Si layers.</p>
},
	keywords = {bulk-heterojunctions, multi-bandgap, near-infrared, quantum dots, solar cells, surface passivation},
	issn = {2194-4288},
	doi = {10.1002/ente.202201375},
	author = {Mahajan, Chandan and Dambhare, Neha V. and Biswas, Arindam and Sharma, Anjali and Shinde, Dipak Dattatray and Rath, Arup K.}
}
@article {49241,
	title = {Solution-phase ligand engineering for all-quantum-dot near-infrared light-emitting diodes},
	journal = {ACS Applied Nano Materials},
	volume = {7},
	year = {2024},
	month = {APR },
	pages = {9126-9135},
	type = {Article},
	abstract = {<p>
	Strong emission over a wide near-infrared (NIR) region makes lead sulfide quantum dots (QDs) a preferred material in building NIR light-emitting diodes (NIR-LEDs) for numerous applications. Narrow-bandgap emitter QDs blended in the matrix of high-band gap QDs offer a simple yet powerful architectural platform for building high-performance NIR-LEDs. So far, the all-QD-based blend architecture has been realized using a poorly controlled solid-state ligand exchange approach. Advanced solution-phase ligand exchange, which offers greater control over surface passivation, is yet to be realized in all-QD LED device construction. We observe that the solution-phase ligand exchange from the optimized lead halide and thiol ligand combination, used in high-performing QD solar cell construction, is inefficient in realizing efficient all-QD LEDs, which could have restricted the adoption of the solution-phase ligand exchange thus far. Here, we introduce an innovative dual-ligand strategy to build all-QD-based NIR-LEDs using an advanced solution-phase ligand exchange approach. Through ligand engineering of matrix QDs, we managed to improve photoluminescence quantum yield (40\%), reduce trap density (10(14) cm(-3)), and prolong carrier lifetime (832 ns). The LED devices benefit from improved electronic properties and balanced carrier injection to yield 6\% EQE and 7.7\% PCE, which are six times higher than those of state-of-the-art ligands.</p>
},
	keywords = {electroluminescence, lead sulfide, ligand passivation, light-emitting diodes, near-infrared, quantumdots},
	doi = {10.1021/acsanm.4c00634},
	author = {Biswas, Arindam and Mitra, Anurag and Sharma, Ashish and Shinde, Dipak Dattatray and Dambhare, V. Neha and Sharma, Anjali and Mahajan, Chandan and Rath, Arup K.}
}
